Disclosed, for example, in International Publication No. WO 97/49235 (reference 1) is a method for employing pixel block coding (PBC) to embed copyright information (hereinafter referred to generally as verification information or embedded data) in data, such as image data, so that the embedded data are not visible (hereinafter this method for embedding verification information in the data contents so that the data can not be seen is referred to as an “electronic watermarking method”).
Disclosed in International Publication No. WO 98/116928 (reference 2) is a method for employing the electronic watermarking method of reference 1 to inhibit the alteration of image data and to effectively protect a literary work.
Further, disclosed in Japanese Unexamined Patent Publication No. Hei 10-164549 (reference 3), as an improvement to the electronic watermarking method presented in reference 1, is a process for invisibly embedding verification information in image data so that alteration of the data can be detected.
In addition to these references, inventions relating to the electronic watermarking method are disclosed in Japanese Unexamined Patent Publication Nos. Hei 09-151747, Hei 10-83310, Hei 10-106149, Hei 10-161933, Hei 10-164349, Hei 10-285562, Hei 10-334272, Hei 10-240626, and Hei 10-240129 (references 4 to 12).
However, the methods disclosed in these references do not take into consideration the compression and coding of image data in which verification information has been embedded. That is, if the verification information embedded using these methods is smaller than a specific quantization value, the embedded data may be lost when quantization is performed.
It is, therefore, one object of the present invention to provide an image processing apparatus and a method therefor that are appropriate for compression coding.
Specifically, it is the object of the present invention to provide an image processing apparatus and method that does not lose embedded verification information, even when a quantization process is performed for image data after the embedding of verification information has been performed.